The use of enzymes to treat animal feed mixes is well known. The treatment of animal feed mixes with enzymes can improve the digestibility of the feed and hence making the feed more efficient and increase its energy content. For example, Hollenbeck in U.S. Pat. Nos. 2,988,949 and 2,988,448 describes the treatment of raw barley feed with barley malt containing cytolytic enzymes; Hollenbeck reports that poultry fed with the treated feed showed improved growth rate because of the increased energy value of the feed. In general, enzymes act to break down feed products, thus increasing the availability of digestible components in the feed to the animal.
However, despite the numerous advantages enzymes have as feed additives, their use in feeds is limited by several drawbacks. One particular problem is the heat instability of most enzymes. It is well known that temperatures approaching 100.degree. C. will in virtually all cases deactivate (permanently) enzymes, and most enzymes will be deactivated if exposed to temperatures approaching 70.degree. C. The heated conditions under which most feed processing takes place inctivates any enzymes present. Elevated temperatures are a characteristic of modern feed processing techniques. In typical feed pelleting processes, the feed is usually "preconditioned" with steam for ten seconds to about three minutes which elevates the temperature to about 70.degree.-80.degree. C. The preconditioning step is followed by pelleting of the feed which takes place at temperatures in the range of 80.degree.-85.degree. C. Other feed processing techniques involve longer "conditioning" and the feed is held at elevated temperatures (60.degree.-95.degree. C.) for periods of five to three minutes. These temperatures (in combination under certain conditions with elevated pressure levels) tends to deactivate unprotected enzymes, even those which may be inherently thermostable. Moreover, the amounts of enzymes which need to be added are extremely small making effective and uniform mixing a serious problem. The difficulty in utilizing enzymes as a feed ingredient is also exacerbated by the fact that mos commercial enzyme products are enzyme solutions which are more difficult to mix than dry ingredients.
One possible solution to these problems is the utilization of pre-mix. Because ingredients such as antibiotics, vitamins, minerals and the like are added to the feed in small quantities, they cannot be added directly to the feed because uniform distribution would be impossible in the context of commercial feed production. A premix consisting of a carrier and active ingredients is generally utilized to introduce these "micro-ingredients" into the feed. Hiller, in U.S. Pat. No. 4,218,437 discloses the use of a feed premix wherein the active ingredients consist of antibiotics in combination with certain enzymes. However, Hiller does not disclose or suggest that the premix discussed could be effectively and efficiently utilized in the large scale commercial production of feed.
Feed premixes--for effective utilization in commercial feed processing--must have certain properties including, inter alia, physical stability, non-interference with the chemical stability of the active product, and good flow and blending properties. To date, no such feed premix containing enzymes has been available for large scale use.
In sum, it has not been simple or cost effective to use enzymes as a feed additive on a large commercial scale.
This invention, however, provides for a relative dry, thermally stable premix which contains one or more enzymes which can be utilized for commercial feed processing. The premix has a high enzyme activity which is not significantly affected by high temperatures used in feed processing "which typically range from about 70.degree.-95.degree. C.". This premix has good flow properties and can be easily and uniformly blended into a feed mixture to effectively improve the properties of the feed.